Sodium Carbonate alone or with black tank chemical?

[jrbdad]

Will the Sodium Carbonate help with odor? Or do I add tank chemical or something else too for that.

On our 4 RV and have been using same chemical for years, but am wanting to try Sodium Carbonate.
Thanks

[therink]

Everyone has an opinion on this but I use nothing but water. My 40 gal black tank lasts for about 7 days with family of 4 and I always start out with at least 5 gals of water in the tank. I also use the black tank flush when dumping and dump, flush and add 5 gals water before heading home each trip. I never have an odor issue. The trick is water and plenty to not let the solids or residue become dry or sludge like in the tank between trips.
Works for me.

[jtyphoid]

I switched last year from commercial chemicals to sodium carbonate and laundry detergent. So far, so good, but our longest time between dump/flush has been about 5 days.

I think that the key question is how long will waste be in your tank before you have an opportunity to dump and flush?

To paraphrase therink, a clean tank doesn't stink.

[theeyres]

Originally Posted by therink

Everyone has an opinion on this but I use nothing but water. My 40 gal black tank lasts for about 7 days with family of 4 and I always start out with at least 5 gals of water in the tank. I also use the black tank flush when dumping and dump, flush and add 5 gals water before heading home each trip. I never have an odor issue. The trick is water and plenty to not let the solids or residue become dry or sludge like in the tank between trips.
Works for me.

Pretty much what I do with the exception that I don't even bother with the black tank flush except when I won't be using the trailer for months. Personally I really don't think the chemicals, sodium carbonate, detergent or anything else helps at all. Just water, water, water.

[JRTJH]

We do the same as Earl, Water is all we add. For us, I think the key is to turn off the exhaust fan before flushing so you don't draw "foul air" down the black tank vent and up through the toilet when the ball valve is open. We've not used any "fragrance chemicals" in the past 4 or 5 years and things seem to "smell the same" and "flush the same" with or without them. With all the environmental issues with formaldehyde, we just quit using anything. That was the last "really effective" additive that controlled odor, IMHO.

[Festus2]

It looks like I am the exception here as I add about 1/2 cup of Calgon, which is mostly sodium carbonate, to about 4 gallons of water and dump that mix down the toilet. The mix has a "slippery" quality to it which, after being sloshed around in the tank while enroute, helps to keep the sides and tank bottom well "lubricated" and helps prevent the buildup of crud on the tank walls.

I must admit however that I have no proof that using Calgon really does help make the sides of the tank "slippery" and I am not about to stick my arm down into the tank and feel the sides to see if they are.

[Javi]

I may give sodium carbonate a try next trip, but looking back all I've ever done was fill, dump, add 5 gallons of water and a goodly dollop of dish detergent to the black tank and grey tank/tanks before heading home.

Once I've settled back into the routine of home, I generally bring the trailer back to the house one Saturday and flush the black tank until I'm satisfied I've got all solids out. I then fill and dump the grey tank/tanks and empty the freshwater tank. That way I can start my next trip preparation routine with filling the fresh water tank and putting 5 gallons of water in the black tank.

[geo]

Ah, where to start? Javi, Festus2, and jtyphoid are all using sodium carbonate in some form and fashion. Sodium carbonate is what is called a "surfactant" – it lowers the "surface tension" of water and makes it easier to "wet" surfaces, thus giving the slick feeling. If you use a detergent, liquid or solid, then you are using soap and sodium carbonate. Yes, it is primarily sodium carbonate that "converts" soap to detergent. Also, many of the OxyClean products contain sodium carbonate. Sodium carbonate is an alkali, so when added to water it increases the pH of the water solution.

So what about sodium carbonate in the black tank? Personally, I use a cup, sometimes two, of sodium carbonate (Washing Soda) in a "freshly" dumped and rinsed black tank along with a "citrus treatment" from Thetford. My black tank is 65 gallons and I dump it once a week for two adults. But what about only using water or water and sodium carbonate?

In the solid wastes, there are plenty of rejected fats and other organics. If you dump often and use a lot of water in the tank, then these fats and organics are diluted to a large extent, so little bacterial action happens to "start stinking" in a short time period. However, adding sodium carbonate to the black tank raises the pH to an alkaline environment. Well, alkalines combined with fats produces "soap" or at least an unpalatable-to-bacteria substance. So, bacterial decay, and smell, will be slowed. So, if one uses detergent with or without sodium carbonate, one is still primarily using the sodium carbonate to convert the fats and organics to something that slows bacterial growth. Actually, Festus2 has a great solution – that of Calgon, since the majority of the volume of Calgon is sodium carbonate along with a trace of fragrance! By slowing bacterial growth with sodium carbonate, the need to use "lots of water" is reduced. Same result – lots of water and dump often to reduce bacterial growth, or moderate water and sodium carbonate and dump reasonably. Plus, adding the "surfactant" (sodium carbonate) will allow the water to "dissolve" the solid wastes quicker because it reduces the water tension on the solid wastes.

Sodium carbonate is a very handy compound for the RVer, as I posted http://www.keystonerv.org/forums/showthread.php?t=1611. However, at the time of that post, I was not aware that Arm & Hammer had changed the packaging to a yellow box. If you look on most any "washing detergent aisle" at the store, you will usually find the Arm & Hammer Washing Soda (yellow box) next to the Arm & Hammer Baking Soda (orange box). If you want clean clothes and a clean black tank, choose the Washing Soda as it is pure non-food quality sodium carbonate. If you want to "sweeten" or deodorize you clothes, then use the baking soda.

Just as a non-RV interesting note: If you have ever taken a raft trip that required all trash and wastes to be removed, such as in the Grand Canyon, then you have experienced the opposite of the "black tank philosophy". On these raft trips, there is a sealed box commonly called "The Groover" in which the solid wastes are collected. These boxes have water-tight seals and are hauled out along with all trash at the raft trip's completion. The goal is to minimize liquids and liquid wastes in these boxes since the lack of additional moisture also retards the growth of "that bacteria"! This is definitely not what you want to happen in a black tank – but it is exactly what you want on an eight day, 277 mile raft trip down the Colorado! My third adventure in the Canyon will be next month.

Ron

[jtyphoid]

Thanks for the detailed explanation, Ron.

So, it sounds like combining laundry detergent with washing soda is just adding soap and some additional washing soda.

I started using the combo when we bought our current trailer and discovered that the previous owners were not properly using or caring for the black tank. It doesn't appear to have a poo pyramid, but it was anything but clean.

Based only on what I can see through a clear elbow when I dump and flush, the combo seems to be helping to clean out the tank. It's taking fewer flush cycles every time. Like festus2, I'm not willing to stick my arm in, so the view through the clear elbow will have to do.

[jrbdad]

Thanks. Ordered some Calgon. will try that.